Learning Forum

[Zhu]

My model is a dissected aorta, where the ascending aorta was replaced by a graft. So my geometry has two parts (Graft and Aorta) and the connection was defined as bonded. I am trying to get the pre-stressed aortic model since the reconstructed geometry was under a diastolic pressure. nFirstly, in Static Structural, I apply a pressure load that equals to diastolic pressure (80 mmHg) and the simulation converged quickly. I exported stresses as text files, which were then imported as inital stress through External Data for another Static Structural analysis. I applied the same boundary conditions toghter with those initial stresses but the solution became unconverged during the first substep as a result of highly distorted mesh. I suppose that the pressure load would counteract with the imported initial stress so there should not be any highly distorted mesh? Anyone suggestions about this would be appreciated a lot!n

[Ashish Khemka]

nnCan you share a snapshot of your setup? Also, what if you do not apply pressure and just see how the model behaves with initial stress?.Regards,nAshish Khemkan

[Zhu]

Hi akhemka,nThanks a lot for your reply! I have attached two figures showing my Setup and Analysis Settings. By the way, my mesh was generated in ICEM and imported through the FEM. nI tried to apply only the initial stress without the pressure load but the same error occurred, still in the first substep. Any further suggestions would be appreciated. nYours,nYunn

[Zhu]

nIn case you haven't noticed my last posting.nYours,nYun

[Ashish Khemka]

nnThe error without pressure load indicates that the elements are distorting when the body relaxes from initially applied stress.Regards,nAshish Khemka